A283753 - OEIS

%I #28 Jan 28 2022 21:52:39

%S 1,1,1,3,4,4,1,1,8,22,37,47,38,27,13,5,1,1,27,108,326,667,1127,1477,

%T 1665,1489,1154,707,379,154,61,16,5,1,1,91,582,2432,7694,19646,42148,

%U 77305,122953,170315,206982,220768,207301,171008,124110,78813,43862,21209,8951,3242,1043,288,76,17,5,1,1,350,3024,17314,74676,266364,808620,2144407

%N Irregular triangular array read by rows: T(n,k) is the number of non-isomorphic unlabeled weakly connected digraphs on n nodes and with k arcs.

%C The range for the subindex k is from n-1 to n(n-1).

%C Obtained from A054733 by removing leading zeros.

%D E. Palmer and F. Harary, Graphical Enumeration, Academic Press, 1973.

%H Marko R. Riedel, <a href="http://math.stackexchange.com/questions/2187019/">Number of distinct connected digraphs</a>

%H Marko Riedel, <a href="/A283753/a283753_1.maple.txt">Maple code for sequences A052283, A283753.</a>

%e First rows are:

%e 1;

%e 1,    1;

%e 3,    4,   4,   1,    1;

%e 8,   22,  37,  47,   38,   27,   13,    5,    1,   1;

%e 27, 108, 326, 667, 1127, 1477, 1665, 1489, 1154, 707, 379, ...

%o (PARI) \\ See A054733 for G, InvEulerMTS.

%o row(n)={Vecrev(polcoef(InvEulerMTS(sum(i=0, n, G(i, y)*x^i, O(x*x^n))), n)/y^(n-1))}

%o { for(n=1, 6, print(row(n))) } \\ _Andrew Howroyd_, Jan 28 2022

%Y Cf. A000273, A000238, A003085, A052283.

%K nonn,tabf

%O 1,4

%A _Marko Riedel_, Mar 15 2017